Unipolar/bipolar operation, Controls – Expert Sleepers Silent Way v2.4.3 User Manual

Page 27

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new instance) which is put in ‘Decoder’ mode. The output of this plug-in is the desired
CV.

Note that the Generator level (see below) defaults to zero so you need to turn it up before
anything will happen. The reason for this is to avoid situations where you might acciden-
tally feed the generated signal out to your speakers and cause damage to your
equipment/hearing/sanity.

Unipolar/Bipolar Operation

CVs can be unipolar - i.e. they take positive values only e.g. 0V-10V - or they
can be bipolar - i.e. they can take both positive and negative values.

Most VCA designs can only handle unipolar CVs. If you want to use Silent
Way CV Input to process bipolar CVs, you have two options:

use hardware modules to scale and bias your CV into a unipolar range (see e.g. the
Doepfer A-183-2 Offset-Generator/Attenuator/Polarizer module).

use a four quadrant multiplier VCA. These are sometimes known as polarizing VCAs
or ring modulators, though the latter is really a misnomer. See e.g. the Doepfer A-133
Dual Voltage Controlled Polarizer or the Cwejman VCO-2RM. NB if the device in
question is described as a ring modulator it should be described as ‘DC coupled’ if
it’s to work with Silent Way CV Input.

If you’re using a four quadrant multiplier, switch the Decoder plug-in to Bipolar mode (i.e.
press the button marked ‘Bipolar’). Note that on some systems the output of the plug-in in
Bipolar mode may be inverted from what you expect - if this is the case, use the ‘Scale’
control to invert the output signal.

Controls

The Generator/Decoder drop-down menu separates the controls for
each channel into two parts, those to the left and right of the menu re-
spectively.

To the left of the menu is the one knob that applies in Generator mode - the
‘Level’ knob. This simply sets the level of the generated signal. As mentioned
above it defaults to zero and must be turned up for anything useful to happen.

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